With recent active studies on genetic engineering technique, various recombinant DNAs and transformants therefrom have been developed. In the preparation of the recombinant DNAs, a vector for inserting a specific gene is used. Such a vector includes a vector which can replicate only in a certain microorganism, e.g. in E. coli, and a socalled shuttle vector which can replicate in two or more kinds of microorganism, e.g. in both E. coli and a yeast, or in both a certain microorganism (e.g. E. coli) and a certain animal cell. For instance, there has very recently been reported a shuttle vector which can replicate in both E. coli and a yeast: a vector utilizing a promoter of alcohol dehydrogenase (ADH1) which is usually used for the production of interferon with a yeast, to which promoter a gene encoding proteins of Hepatitits B virus surface antigen (hereinafter, referred to as "HBs antigen", or "HBsAg" or "s antigen") is inserted [cf. Nature, 298, 347-350 (22 Jul., 1982)]. However, the shuttle vector used in this method carries an ADH1 promoter and, when a recombinant DNA inserted with HBs gene is prepared by utilizing the vector and then a transformant is prepared from the recombinant DNA, the transformant can produce the desired HBs proteins only in a small amount.
The present inventors had extensively studied on an improved E. coli-yeast shuttle vector which can be recombined with various genes and can express them. As a result, it had been found that a specific shuttle vector having a yeast gene and an E. coli gene and carrying the repressible acid phosphatase promoter of the yeast has desired characteristics and is useful for recombining various genes under the control of the phosphatase promoter to prepare recombinant DNAs which can give various transformed yeasts [cf. Japanese Patent Application No. 145093/1982, U.S. Ser. No. 522,668, Canadian Patent Application No. 435007, European Patent publication No. 0103201, and Korean Patent Application No. 83-3854].
The above-mentioned shuttle vector includes shuttle vector pAT77 wherein a yeast DNA containing ars 1 (which is a DNA sequence necessary for the autonomous replication of the yeast), 2 .mu.ori (which is a DNA sequence necessary for the replication of 2 .mu.m DNA, and Leu 2 (leucine-producing gene) as the yeast gene is combined with E. coli plasmid pBR322; and shuttle vectors derived from the shuttle vector pAT77 by treating it with an exonuclease BAL 31 to delete a part or whole of the structural gene of acid phosphatase and further optionally various regions upstream therefrom (usually from +1 to -100 bp), for example, shuttle vector pAM82 wherein upstream till -33 bp is deleted. The shuttle vector pAM82 has a structure as shown in the accompanying FIG. 1, wherein the thick line region is the gene originated from E. coli plasmid pBR322 and the remainder region is the gene of a yeast.